Manufacture of metal-free phthalocyanine



Patented Oct. 18, 1949 2,485,16 ICE MANUFACTURE OF METAL-FR E PHTHALOCYANIN E William Llewlyn Rintelman, Glassboro, N. J assignor to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application April 1, 1948, Serial No. 18,492

Claims.

This invention relates to the production of metal-free phthalocyanines. More particularly, this invention deals with an improved catalytic process for making metal-free phthalocyanines directly from the corresponding phthalonitriles.

Metal-free phthalocyanine, which is the common name for what is strictly speaking dihydrogen-phthalocyanine, has heretofore been prepared by two principal methods. In the indirect method, a metal phthalocyanine is first formed and the metal is then replaced by hydrogen by special treatment. Thus, in Thorpe et al., U. S. P. 2,000,051, metal-free phthalocyanine was produced from ortho-cyanobenzamide by preparing first magnesium phthalocyanine and treating the latter with concentrated sulfuric acid. According to the same patent, if antimony is employed in the synthesis in lieu of magnesium, metal-free phthalocyanine results directly. In U. S. P. 2,000,- 052, the same pigments were prepared from magnesium and antimony, respectively, using phthalimide in lieu of o-cyanobenzamide.

In U. S. P. 2,202,632 issued to I-Ieilbron et al., phthalonitrile is employed as initial material; but this is converted first into the phthalocyanine of calcium, barium, magnesium, cadmium or beryllium by reaction with the respective metal or an oxide or salt thereof, and the metal phthalocyanine is then converted into the metal-free compound by treatment with concentrated sulfuric acid.

In Dents U. S. P. 2,214,454, a commercial process for manufacturing metal-free phthalocyanine is proposed wherein phthalonitrile is first converted into sodiumor potassium-phthalocyanine by reaction with the respective metal in boiling amyl alcohol, according to U. S. P., 2,116,- 602, and the pigment is then extracted with methyl alcohol and Water, resulting in the metal-free compound.

In the second principal method, attempts have been made to prepare dihydrogen-phthalocyanine directly from phthalonitrile or other phthalocyanine-yielding intermediates, by the aid of catalysts. The first attempt along these lines I find in Heilbron et al., U. S. P. 2,116,602, wherein the reaction was carried out in quinoline or dimethylaniline as a solvent, and ammonia was employed as catalyst.

An attempt was also indicated there at converting molten phthalonitrile into pigment in the absence of a solvent, but using ammonia as catalyst.

A second attempt wherein no solvent was employed, was indicated in Lowes U. S. P. 2,155,054.

Here, the phthalonitrile was fused, and mono-,

2 the presence of an alkali-metal or alkaline-earth hydroxide, using methylglucamine as catalyst.

All the above procedures nevertheless suffer from poor yields, poor quality of the product, or else too many manipulative steps which render the process costly on a large scale.

Accordingly, it is an object of this invention to provide an improved process for producing metaliree'phthalocyanine by a direct method and usin inert organic solvents. A further object is to provide a process for the commercial production of metal-free phthalocyanine in good yield and high quality. A still further object is to produce metalfree phthalocyanine by a process which results in a crystalline product contained in an organic liquid, whereby recovery may be effected directly by the simple process of filtration and Washing. Other and further important objects of this invention will appear as the description proceeds.

In my copending application of even date herewith, Serial No. 18,491, now U. S. Patent 2,485,167, a method is proposed for achieving the above objects by carrying out the synthesis from standard material, to wit phthalonitrile or a substitution derivative thereof, using an inert organic solvent, for instance trichloro benzene, and using as catalyst a limited quantity of an organic nitrogenous base whose dissociation constant K has a value between 2x 10- and 2 10- The reaction temperature employed there is between 185 and 230 C.

Now I- find that the above process can be further improved by selecting piperidine or a homolog thereof as the base and adding to the reaction mass a relatively small quantity of ethylene glycol in conjunction with a small quantity of an alkalimetal carbonate. The advantages gained thereby is that the reaction temperature may be considerably reduced, resulting in a product of superior quality. Also, lower boiling solvents may be employed, without resort to pressure.

The quantity of piperidine or its homolog to be employed according to this invention is preferably kept between about 7 and 20 parts by weight for each parts of o-arylene dicyanide employed. The quantity of ethylene glycol may be about 2 to '7 parts on the same scale, while the quantity of carbonate is of the order of 0.5 to 5% based on the weight of the dicyanide. The preferred temperature of reaction is in the range of to C.

Apart from the above limitations as to the nature of the catalysts and their quanties, the reaction in my improved process may follow standard practice. For instance, the quantity of solvent may be any convenient quantity sufficient to dissolve the initial phthalonitrile. As such solvent, any inert, water-immiscible organic liquid which is a solvent for the o-arylene dicyanide selected, may be employed, for instance trichlorobenzene, diphlorobenzfene, benzene, toluene, solvent naphtha, cyclohexanol or molten naphth'alene; and where the boiling point of the organic solvent is lower than the desired reaction temperature, the reaction may be carried out under autogenous pressure in a closed vessel.

The process may be applied to phthal itself, to produce metal-freephthalgcyan it may be applied to substitution derivat nitrile phthalonitrile to produce cor e pondinglys bstituted metal-free phthalocyanines. As instances of such substituted phthalonitriles may be mentioned: 3- or 4-chloro-phalonitrile, 4,5;dichlorqphtlralon-itrile, 3- or l-nitro-phthalonitrile, the cyano;phthalonitriles, the mercapto-phthalonitrues, iethyl-phthalonitriles, phenyl-phth'al'onitrileetc.

. The reeevery of the dyestufi in my improved 13,000 parts of ortho-dichlor-benzene at 155-165 C.

andheld at this temperature until 9.11 traces of moisture have been drivenoff. Then 12 parts, of potassium ,carbonateare added, followed by :103

parts -of piperidine.v The mass is stirred at this temperature forv .10 to 30 minutes. 44.4 parts of .ethyleneglycol are then slowly added (over, 1:2 .hour period). The temperature rises during this addition. to 17 -1'75" ,C. as the reaction proceeds.

free phthalocyanine, which comprises heating an The temperature is held between 170175 C. for

,.-12 to, 16. hours longer and then cooled to 100? C.

,-,'Ifl: 1e thick. magma, is filtered off with suction,

washed 4, times with dichlorbenzene, and then -dried i a a1r..ov n.. AW- 0 T .color is pur t a d i d of .78.

Y ....1hste d.or d yin t e a di y, the resid e solvent maybe removed byan alcohol washer obtained in crystalline form, in a high state of it may be removed by steam distillation and then 3 ie ,lnste ad of piperidine in the above example, alpha -pipecoline may be used, without any difference in yield and quality of the product.

Example 2 100. parts ,of phthalonitrile, 1 part of potassium 4 carbonate, 8.6 parts of piperidine, 3 parts of ethylene glycol and 300 parts of cyclohexan ol are l h'eated'at 160.165 (3., under gentle reflux,'f.or 20 to' .3 0 hours. The reaction mass is then filtered at 140-160? C. with suction, and washed with. hot cyclohexanol,untiljthefiltrate is colorless. The "adhering cyclohexanol is then washed outwith ethyl alcohol, and the cake is dried. The yield "of pure color crystals obtained is about 73 to 75%.

I Example 3 1A matured 150 parts er 4-nitroj-phthalonitrile and 585 parts of o-dichlorobenzene was ethylenefglycol were added in the order named. The mixture was heated to 177-* '-2 c. and held there for 18 hours. The product was cooled to 125 C., filtered, washed with hot o-dichlorobenzen "and alcohol and dried to give 114 parts of a product consisting mainly of tetra-(4)-nitro-dihydrqgen-phthal o cyanine.

rt w ili h undeiistood that 'the details of proecedure may be varied within wide limits, without departing from the spirit Of this invention.

in lieu of potassium carbonate, sodium carbonate may be employed.

,,The -.;Ineta1-free phthalocy-anine obtained by this invention may be used for the preparation of h qua litypigment pastas and. powders, for use imprinting ink's, 'in 'teiitiledyeing, peter colr ng, e c, ,1.

M invention' fiirni'shs "a 'inore economical process ibfffpfeparing a very pure. product in higher yields than heretofo're realized, It also the advantage foffgivirlg material having a much greener and brighter shade than that previouslylobtained. I

I claim as my invention; K

1. "A process for the manufacture of a metalorthoarylene dicyanide of the benzene series in an inert'orga'riic solvent and in thepresence of an organic nitrogenousbas selected from the group consisting of piperidine and the pipecolines, and in the further presencebf glycoland of an alkalimetal carbonate.

. 2. Aprocess'as inlclaiin '1, wherein the quanitity of nitrogenous basejseleoted'is not'over 20% by weight of'theforthoarylene dicyanide, and the "quantity of the glycol is not over 7 by weight on the same basis.

d 3. Ap roce ss *asin claim}. wherein the reaction is conducted'at a temperature not exceeding a 4. A process for theimaniifacturebf a metalf ree phthalocyanine which comprises heating an orth'oarylene dioyanide of the benzene series at a temperature between 1 60 and 180 C. in an inert 'or ganic solventfin the presence of a nitrogenousbase selected from the group consisting of piperidine andthe-pipecolines taken in quantity 'offrom 7 to 20% by weight of the orthoarylene dicyani'de"beiiig treated, andin' the further presence of from 2 to? by weight of ethylene glycol and from 0.5 to 5% 'of an alkali metal carbonate,

the peroentages'beingbased on'the weight of the i onthoary'lene d'icyanide.

heated for 1 hour'at C. The temperature '70 was" raised to 1 60 C., and 12.8 parts of piperidine, 1.2 parts of potassium carbonate and 5.0 pants of 5. The probess of preparing'metal-free phthalocyanine, which comprises heating substantially 100 parts'by weight'bf phthal'onitrile, at to 1805C; in a quantityfof o-dichlor'obenzene suflicient to dissolve the seuiqehd i the further presence of from? to 20 parts "of piperidine,'from 2 to'lpar ts ofethylene glycoland'about 1 part of potassium carbonate, and recovering the crystalline color thus obtained.

WILLIAM "LLEWLYN RINTELMAN.

Y D REFERENCES CITED Thefollowing references"are of record in the "file'of this patent:

UNITED STATES PATENTS Theme Date Number I V Lowe Apr. 18, 1939 

